Because block-argument is actually the “right way”. The phi-node is very un-natural.. in the same sort of way that pi should have been tau. Also, notice the co

Because block-argument is actually the “right way”. The phi-node is very un-natural.. in the same sort of way that pi should have been tau. Also, notice the connection here between Phi nodes and Continuation Passing Style (CPS). It because obvious with the block-arg form because it’s just the same thing. Jumps to blocks are just calls that don’t return.